Torsion counterbalance with cable pretensioning device

ABSTRACT

A COUNTERBALANCE WITH A CABLE PRETENSIONING DEVICE WHICH IS PARTICULARLY ADAPTABLE TO TORSION SPRING COUNTERBALANCES OR ROTARY SHAFT DRIVEN LIFT GARAGE DOORS OR THE LIKE TO PREVENT UNDUE SLACK IN THE WINCH LINES OR CABLES. THE COUPLING BETWEEN THE CABLE DRUM AND THE MEANS WHICH DRIVES THE DRUM PERMITS LIMITED RELATIVE ROTARY MOVEMENT. THE COUPLING IS PREFERABLY SPRING BIASED SUCH THAT THE WINDING DRUM IS BIASED FOR ROTATION IN ITS WIND-UP DIRECTION RELATIVE TO THE DRIVE SIDE OF THE COUPLING.

A. O. ELLIOTT Oct. 26, 1971 TORSION COUNTERBALANCE WITH CABLE PRETENSIONING DEVICE Filed Deo. 9, 1968 H15 A fro/auf Ys ELL.'

United States Patent O 3,615,065 TORSION COUNTERBALANCE WITH CABLE PRETENSIONING DEVICE Adelma O. Elliott, 1130 Osterhout Road, Kalamazoo, Mich. 49002 Filed Dec. 9, 1968, Ser. No. 782,168 Int. Cl. B651! 75/48 U.S. Cl. 242-107 8 Claims ABSTRACT OF THE DISCLOSURE A counterbalance with a cable pretensioning device which is particular-ly adaptable to torsion spring counterbalances or rotary shaft driven lift garage doors or the like to prevent undue slack in the winch lines or cables. The coupling between the cable drum and the means which drives the drum permits limited relative rotary movement. The coupling is preferably spring biased such that the winding drum is biased for rotation in its Wind-up direction relative to the drive side of the coupling.

BACKGROUND OF THE INVENTION This invention relates generally to winching devices and more particularly to a winding drum device found in torsion drive or counterbalance assemblies for lift garage doors and the like.

In the lift type garage door industry, torsion spring counterbalance assemblies are commonly employed to counterbalance the weight of the door. The most prevalent use of such counterbalance assemblies is found in residential and commercial sectional garage doors which are suspended on overhead tracks when the door is in the up position.

The most Widely accepted torsion counterbalance assembly consists of a shaft which is journaled for rotation in two or more mounts which are generally secured to the wall above the door opening such that the shaft runs parallel with the door lintel.

Cable drums are rigidly secured on each end of the tubular shaft and a cable is secured to and wound about each of the cable drums in the same rotational direction with the free end of each cable being secured to the bottom panel or section of the sectional lift door. A coiled torsion counterbalance spring is placed over the shaft with one end secured relative to the door lintel and the other end adjustably secured to the shaft so that the torsion spring may be pretensioned to the desired degree and thereafter secured or locked relative to the shaft. The counterbalance torsion spring has a coil Wind which is compatible with the drums such that when it is pretensioned it will urge the drums to rotate in their cable take-up direction. As the door is lowered from its overhead position, its wei-ght is increasingly shifted from the overhead tracks to the cables. To counterbalance this, the torsion spring is simultaneously wound tighter via the cable drums and shaft.

A common fault has plagued the above described counterbalance system for many years in that when for some reason the movement of one side of the door is restricted upon lowering, such as by binding in its guide tracks or upon engaging an object lying thereunder, the cable on that side becomes slack and dislodges itself off of the cable drum which is specifically surface contoured or tapered and designed for the specific door and track arrangement to be installed. The door then becomes completely inoperable thereby restricting ingress and egress which can seriously hinder the working conditions of the user until the proper service can be obtained which is both time consuming and expensive.

The principal object of the present invention is to obviate the foregoing problems by the provision of a novel winding drum arrangement whereby undue yslack in the line or cable is prevented.

SUMMARY OF THE INVENTION The winching device of the present invention has its primary application and finds its most novel combination in torsion counterbalance systems for lift type doors however it need not be limited thereto and it Will become obvious upon reading the following disclosure that it can be readily adapted for use with any Winch or winch type device where slack cable is not desired.

The winching device of the present invention generally comprises a Winding drum mounted for axial rotation and which has a winch line secured thereto for winding thereon and drive means coupled to the drum to impart axial rotation to the same. This assembly is characterized in that the coupling between the drum and the drive means permits limited relative rotary movement therebetween. Thus, for example, in the torsion counterbalance assembly as aforedescribed with a single or continuous shaft, when one side of the garage door is not permitted to drop evenly with the other, the coupling between the drum and the shaft or torsion spring will permit relative movement therebetween on the side which is obstructed such that the cable drum on that side will not continue to rotate with the shaft thereby preventing undue slack in the cable which would cause the same to dislodge itself from the winding surface of the drum.

In the preferred embodiment of the present invention a spring means is secured between the drum and the shaft to bias the drum for rotation relative to the shaft in its cable or which line Wind-up direction thereby imparting positive wind-up rotation to the drum relative to the shaft to -keep the cable or winch line taut. The spring means under normal operation of a garage door, for example, would not come into play because under normal conditions the torsion counterbalance spring overpowers the spring means which biases the coupling between the shaft and the drum.

The spring means is preferably a coiled torsion spring which is pretensioned somewhat similar to the torsion counterbalance spring as previously described.

Another principal object of the present invention is to provide a torsion counterbalance for a lift garage door or the like which comprises a support and a shaft journaled to the support for axial rotation and a pair of spaced winding drums mounted on the shaft adjacent its ends for rotary movement with the shaft. Each drum is provided with a winch line which is secured thereto and Wound about its winding surface yon each drum respectively in the same rotational direction. A torque conversion means is secured between the support and the shaft to either counterbalance the torque to be applied to said shaft through the winch lines and drums as by a torsion spring for example, or to rotatably drive or brake the shaft as by a fluid drive unit for example. A coupling means is provided between each of the drums and the shaft to permit `limited relative rotary movement and driving engagement therebetween. Here also it is preferred, but not necessary, that a spring means be secured between each of the drums and the shaft to bias the drums for axial rotation relative to the shaft in their winch line take up direction.

The torsion counterbalance may be further characterized by providing a sleeve fixed on the shaft for each drum. Each drum and its corresponding sleeve are provided with interengaging abutments to limit the axial rotation of the drum on the shaft thereby providing the aforementioned coupling means.

Another object of the present invention is to provide the aforementioned sleeve such that it is coaxially received within the drum or drum hub with a projection radially extending from the sleeve and received in an annular guide or groove or the like in the drum. The annular guide has abutments at both ends to engage the projection to limit the relative rotary movement.

This invention is further characterized in that the projection may also be a lock bolt threadably received through the sleeve to engage the shaft and tix the sleeve relative thereto.

The present invention is intended in the preferred combination for use in combination with any torsion counterbalance or torsion drive system (either of which or the combination of which is referred to generically as a torque conversion means) for lift garage doors and the like. For example, the torsion counterbalance need not necessarily be a torsion spring as previously described. Some lift doors employ a series of static weights which may be attached periodically to a chain line or loop or other exible line means which has its free end secured to and wrapped about a drum secured to the torsion shaft. The weights rest upon one or more support surfaces when the door is up or open, and as the door is lowered the weight of the series of weights is progressively transferred to the chain or flexible line to increase the counterbalance torque applied to the torsion shaft via the drum to which the chain free end is secured.

When the torque conversion means includes an automatic operator, such as an electric or hydraulic operator, connected to directly drive the torsion shaft as by a chain and sprocket assembly to eliminate manual lifting and lowering of the door, the winching device of the present invention also plays an important role in addition to that already described. When the automatic operator applies more torque to the torsion shaft to lower the door than does the free fall weight of the door itself, then the relative rotary movement provided in the assembly permits the operator to overdrive the torsion shaft to prevent slack and dislodged cables.

Other objects and advantages appear hereinafter in the following description and claims.

The accompanying drawings show, for the purpose of exemplication without limiting the invention or the claims thereto, certain practical embodiments illustrating the principles of this invention wherein:

FIG. 1 is a view in front elevation of a torsion spring counterbalance in partial section for a lift garage door or the like illustrating one embodiment of the present invention.

FIG. 2a is a perspective view of a locking sleeve employed with the winding drum illustrated at the left side of FIG. 1.

FIG. 2b is a perspective view of the inside winding drum hub employed in the winding drum illustrated at the right side of FIG. l.

FIG. 3 is a view in front elevation of a torsion spring counterbalance for lift garage doors and the like in partial section illustrating other embodiments of the present invention.

As previously stated, the present invention may be employed with any winching device. However, the present invention is herein illustrated in its preferred application as incorporated in torsion counterbalance systems for lift clearance garage doors and the like and together they provide a very novel combination. It will 'become obvious that the teachings of the present invention may be readily employed in other continuous shaft winching devices with two or more spaced drums wherein it is desired to maintain the winch line or cable taut or to prevent the same from dislodging itself from the winding reel or drum.

Referring to the torsion counterbalance system illustrated in FIG. 1, tubular shaft 1 is journaled for axial rotation adjacent its opposite ends in head brackets 2 by bearings 3. Head brackets 2 are L-shaped brackets having their respective feet 4 secured by lag bolts 5 or the like to a support which is generally a building structure or wall.

The shaft 1 is mounted by brackets 2 such that it is immediately above and lies in parallel with the lintel of a door opening.

Mounting drums 6 and 6 are mounted for axial rotation on tubular shaft 1 at the left and right ends thereof respectively. Each of the drums 6 and 6 are provided with the sleeve bearing 7 to permit axial rotation on shaft 1. Under normal circumstances, the internal surfaces of the drums themselves may provide a sucient bearing surface.

The drums 6.and 6 are generally cast of a light alloy metal and provided with their respective coaxial Winding surfaces 8 and 8 to receive cable 10 and 10' respectively.

The cable or winch line winding surface 8 has a lefthand thread 9 to receive cable 10 therein, and winding surface 8 is provided with a right-hand winding thread 9 to receive cable 10 therein.

Each of the cables 10 and 10' are secured to their respective drums by passing the same through an opening 11 adjacent the outer end of each drum and thereafter securing the end with a cable clamp 12 or the like to prevent the cable from dislodging itself from opening or passage 11. Although cables 10 and 10' are wound about their respective drums in opposite ywinding directions, they are both wound in the same rotational direction.

The drums 6 and 6 are generally cast with the annular recesses 13 and 14 which leave the supporting web 15, outside hub 16 and inside hub 17 to prevent unnecessary material waste.

Radially extending webs 18, which are periodically dispersed about the cavity or recess 14, are also provided by the casting process to increase the strength of each of the drums 6 and 6.

Each drum 6 and 6' is provided with a locking sleeve 19 which is adjustably securable to tubular shaft 1 by means of set screw 20 which is threadably received through the sleeve 19 to engage shaft 1 and thereby secure sleeve 19 relative thereto and for rotation therewith. A detailed view in perspective of sleeve 19 is shown in FIG. 2a.

Locking sleeve 19 is provided with projection 21 which is merely an unremoved annular portion of the sleeve 19 itself. Projection 21 is here illustrated as extending approximately about the end perimeter of sleeve 19.

Each of the hubs 17 of the drums 6 and 6 are provided with similar mating projections 22 which are likewise formed by cutting out or removing an annular segment of the tubular hub 17.

Hubs 17 are therefore permitted to interengage with locking sleeves 19 by projections 22 and 21 which provide engagable abutments 23 and 24 respectively as best illustrated in FIG. 2.

As illustrated in FIG. 1, the projections 22 of the hubs 17 are permitted to extend about the perimeter of the hub for approximately 90 as is the reciprocal projection of sleeves 19.

It is thus readily observed that the locking sleeves 19 limit the axial rotation of drums 6 and 6 on shaft 1. In this instance the axial rotation of drums 6 and 6 on shaft 1 is limited to approximately 180. It is obvious that the perimetral extension of each of the projections 21 and 22 may be varied as desired to accordingly vary the limit of axial rotation for each of the drums 6 and 6 on shaft 1.

The counterbalance is provided with a torque conversion means or rotary drive means which in this instance consists of right Iwound torsion spring 25 which lies over shaft 1 and is adjustably secured to shaft 1 by the spring winding plug 26 which may be rigidly secured to shaft 1 by means of set screws 27.

The other end of torsion spring 25 is secured to anchor plug 28 which is in turn secured to the L-shaped spring anchor bracket Z9 by means of bolts 30. Spring anchor bracket 29 is in turn secured to the same stationary support provided above the door opening to which brackets 2 are secured by means of lag bolts or screws 5.

Spring anchor bracket 29 may also be provided with bearing 32 to rotatably receive and aid in supporting shaft 1 which passes therethrough.

Torsion spring being rigidly secured at one end to spring winding plug 26, may be pretensioned by rotating spring winding plug 26 counter clockwise as viewed from the left side of FIG. l and thereafter securing plug 26 rigidly with shaft 1 by tightening down set screw 27. Holes 33 are provided in plug 26 to receive the end of a leverage bar or the like to permit easy rotation of plug 26.

The coupling provided by hub 17 and sleeve 19 of drum 6 is spring biased by means of right wound torsion spring 34 to bias drum 6 for rotation relative to shaft 1 in its winch line or cable wind-up direction. Spring 34 is secured at one end to drum 6 by passing the same through an opening in cast web 41 and bending the spring end over. The other end is secured to sleeve 19 by inserting the spring end into tight engagement with bore 42.

Cable 10 extends downwardly and would normally connect to the bottom panel of a sectional lift garage door or the like of the conventional type which is supported at its side ends by rollers which are received in tracks 35 which extend vertically with the opening and project inwardly and horizontally overhead to receive the door when the same is opened or in the up position.

As the door is lowered all or a good portion of its weight is applied to cable 10 which in turn creates a relatively large torque on winding drum 6 which is larger than the torsional strength of spring 34 and thereby overcomes the same to permit abutments 23 and 24 of hub 17 and sleeve 19 respectively to continually engage as both drums 6 and 6 and shaft 1 rotate to permit cables 10 and 10 to unwind and lower the door. However, if for any reason cable 10 should become slack, and shaft 1 should continue to rotate in the counter' clockwise direction as viewed from the left of FIG. 1 by reason of the torque applied to drum 6 at the right, then torsion spring 34 will come into effect to urge drum 6 to rotate in the clockwise direction, as viewed from the left of FIG. 1, within the limits of the relative rotary movement permitted between the shaft 1 and drum -6 to keep cable 10 taut or to prevent undue slack therein.

It should be noted that the winding drum 6 illustrated at the right of FIG. 1, is provided with no torsion biasing means or spring 34 as illustrated in connection with winding drum 6. This is to illustrate that spring 34 is not necessary but is preferred. Thus if cable 10 becomes slack for any reason, as Where an object may be lying upon the ground where the door strikes a closure at the right end, and shaft 1 continues to rotate in the counter clockwise direction as viewed from the left end of =FIG. l by reason of the torque applied to winding drum 6 via cable 10, then the limited relative rotary movement between winding drum 6 and shaft 1 will permit drum 6 to discontinue its rotation while shaft 1 continues to rotate for a short period. In this instance, the cable 10 is not kept taut but undue slack therein is prevented which would otherwise cause cable 10 to become dislodged from its proper setting in the winding surface thread 9' which is engineered to have a specic drum taper to provide the proper relationships between the doorway at any given position relative to its counterbalance provided by counterbalance torsion spring 25. Thus if the cable 10 or 10' becomes dislodged from its proper position on its respective drum winding surface, the counterbalance becomes inoperative or at least improper.

FIG. 3 illustrates a structural variation of the present invention which is in many instances similar to that illustrated in FIG. 1. Therefore, like elements are `given the same reference numerals.

In viewing drum 6 at the left of FIG. 3, the locking sleeve 19 is positioned coaxially or received coaxially within hub 17 and secured to or fixed with shaft 1 by means of set screw 20 which in this instance is an Allen screw which also provides the projection 21 which is received in annular slot or guide 36 in hub 17. Annular slot 36 extends around hub 17 for a desired number of degrees as say from to 340 for example to provide abutment surfaces at either end thereof for engagement with projection 21 provided by Allen screw 20. In this manner relative rotary movement is permitted between shaft 1 and drum 6.

The structure of drum 6 as seen in FIG. 3 also has the added advantage over that seen in FIG. l in that projection 21 also limits the axial allowable movement of drum 6. In FIG. 1, this movement is limited alone by the adjacent header plate 2.

A small clearance 37 is permitted between hub 17 and sleeve 19 to prevent any frictional engagement therebetween.

Right wound ribbon spring 34 is secured at one end to sleeve 19 as indicated at 38 and is secured at its other end to hub 17 as indicated at 39.

The coupling structure shown in connection with the winding drum "6 as seen at the right side of IFIG. 3, iS substantially identical to that of the structure shown at the left side of FIG. 3 with the exception that sleeve 19 is provided with radial projection 21 which is merely a dial extension and does not provide a set screw in combination as set screw 20 provided on the extended end of sleeve 19 which extends beyond the end of hub 17.

The structure of drum -6 at the right of .F-IG. 3 also differs from that shown at the left in that slot 40 is provided in the hub 17 horizontally to engage with slot 36 thereby permitting easy insertion and removal of sleeve 19 together with projection 21.

In this instance torsion spring 34", which is a left wound spring, is secured at one end to sleeve 19' and at the other end to hub 17 to bias the coupling therebetween. The structure of this arrangement readily permits one installing the structure to rotate sleeve 19 counterclockwise on shaft 1, as viewed from the left end of the ligure, to pretension torsion spring 34 fbefore sliding sleeve 19 axially to the right as seen in the gure such that projection 21 is permitted to pass through slot 40 and into slot 36, in a bayonet lock fashion, after which screw 20 is tightened down. This permits quick and easy installation and service of the apparatus.

The coupling between the drum and the drive means or torsion counterbalance which provides the relative rotary movement need not necessarily be between the drum and the shaft as is disclosed in the figures. For example, the drum may be rigidly secured to the shaft and the limited relative rotary movement may be provided in a shaft spline disposed somewhere between the ends of the shaft 1 with the torsion counterbalance engaging the shaft on the opposite side from. The spline coupling should also be spring biased as taught hereinbefore.

I claim:

1. A duplex winching device comprising a shaft journaled for axial rotation, a winding drum mounted on each end of said shaft for rotary movement therewith, a winch line secured to each of said drums for winding thereon, counterbalance drive means coupled to said shaft to impart axial rotation thereto, characterized by a coupling between said drive means and at least one of said drums which permits limited relative rotary movement therebetween, and spring means normally overpowered by said counterbalance drive means when a load is applied to said winch lines and biasing each of said couplings to bias their respective drums for rotation relative to said shaft in their winch line wind-up direction.

2. A torsion counterbalance for a lift garage door or the like comprising a support, a shaft journaled to said support for axial rotation, a pair of spaced winding drums mounted on said shaft adjacent the ends thereof for rotary movement therewith, a winch line secured to each of said drums and wound thereabout in the same rotational direction, torque conversion means secured between said support and said shaft to counterbalance the torque to be applied to said shaft through said winch lines and said drums, characterized by coupling means between each of said drums and said shaft permitting limited relative rotary movement therebetween, and spring means normally overpowered by said torque conversion means when a load is applied to said Winch lines and secured between each of said drums and said shaft to bias said drums for axial rotation relative to said shaft in their Winch line take-up direction.

3. The torsion counterbalance of claim 2 characterized in that said torque conversion means consists of at least one torsion counterbalance spring coiled about said shaft and having one end secured relative to said support and the other end adjustably secured to said shaft, said torsion spring being pretensioned to overcome said spring means when a load is applied to said Winch lines and urge said drums to rotate in their take-up direction.

4. The torsion counterbalance of claim 3 characterized by a sleeve xed on said shaft for and adjacent each of said drums, each of said drums and their respective of said sleeves having interengaging abutments of limited circumferential extent t limit the axial rotation of said drum on said shaft and thereby provide said coupling means.

5. A cable drum device for mounting on a shaft in a torsion counterbalance assembly for lift garage doors and the like comprising torsion counterbalance means secured to said shaft to counterbalance torsional loads to be applied thereto, a cable drum journaled for axial rotation on said shaft, a sleeve xed on said shaft, said drum and said sleeve having engageable abutments of limited circumferential extent to limit the axial rotation of said drum on said shaft, said sleeve being coaxially received within said drum and provided with a radially extending projection received in an annular guide in said drum having abutments at both ends thereof to engage said projection, to provide said engageable abutments, said projection consisting of a lock bolt threadably received through said sleeve to engage said shaft and fix said sleeve relative thereto.

6. A cable drum device for mounting on a shaft in a torsion counterbalance assembly for lift garage doors and the like comprising torsion counterbalance means secured to said shaft to counterbalance torsional loads to be applied thereto, a cable drum journaled for axial rotation on said shaft, a sleeve fixed on said shaft, said drum and said said sleeve having engageable abutments of limited circumferential extent to limit the axial rotation of said drum on said shaft, said sleeve being coaxially received within said drum and provided with a radially extending projection received in an annular guide in said drum having abutments at both ends thereof to engage said projection to provide said engageable abutments, and an axially extending guide communicating with said annular guide with the exterior end of said drum to permit access of said projection therethrough from the exterior into said annular guide.

7. A torsion counterbalance for a lift door comprising,

a support,

a shaft supported by and journaled to said support for axial rotation,

a pair of spaced winding drums mounted on said shaft adjacent the ends thereof,

a cable for each drum having one end secured to its respective drum for winding thereabout and its other end free for attachment to a lift door,

counterbalance means anchored to said support and operably connected to said shaft to counterbalance a load to be applied to said cables,

a limited movement rotary coupling means operative to permit limited relative rotary movement between each of said drums and said shaft,

and spring means biasing said coupling means to continually urge said drums to rotate in their cable wind-up direction,

said spring means exerting a small torque sufficient for tensioning said cables as compared to the large counterbalance torque exerted by said counterbalance means.

8. A torsion spring counterbalance for a lift door comprising,

a support,

a continuous shaft supported by and journaled to said support for axial rotation,

a pair of spaced winding drums journaled for axial rotation on said shaft adjacent the ends thereof,

a cable for each drum having one end secured to its respective drum for winding thereabout and its other end free for attachment to a lift door,

a torsion counterbalance spring coaxially received over said shaft and having one end secured relative to said support and the other end adjustably secured to said shaft and wound to urge said drums to rotate in their wind-up direction when said spring is unwinding,

a limited movement rotary coupling between each of said drums and said shaft,

said coupling having interengaging projections of limited circumferential extent to provide said limited rotary movement and provide driving engagement between said shaft and said drums,

a cable tension spring biasing each of said couplings to urge said drums to rotate in their wind-up direction,

said cable tension spring exerting a small torque on said drums suicient for tensioning said cables as cornpared to the large torque transmitted from said torsion counterbalance spring to said drums.

References Cited UNITED STATES PATENTS 1,992,006 2/1935 Greegor 160-191 X 2,233,539 3/1941 Landrum 64-27 2,616,274 11/1952. Landrum 64-27 2,861,630 11/1958 Baker 160-191 X 3,043,259 7/1962 Sadler 242-865 X 3,412,423 11/196'8 Binns 160--191 X FOREIGN PATENTS 703,965 2/1954 Great Britain 16--198 718,037 2/1942 Germany 242-107.13

STANLEY N. GILREATH, Primary Examiner W. H. SCHROEDER, Assistant Examiner UNTED STATES MTENT @Fm-'CE CERT'FICATE 0F CORRECTEN Patent No. 3:615'055 Dated OCtOber 25 9 1971 ADELMA O. ELLOTT Inventor(s) It is certified that error a ppears in the above-identified patent and that said Letters Patent are hereby correcte as shown below:

Column 6, Claim l, line 65 "drive means line 69 delete each of'; line 69 -coupling; line 7G their 'drums' should be drum;

'couplings' should be should be its; line 70 Column 8, Claim 7, line 2 delete a'al djacent the ends thereof': line 32 after "wound" insert --unde r tension-- Signed and sealed this 25th day of April 1972.

{SEAL} Attest:

LEDEMRD Ef1.FL1LTCHEH, JH. ROBERT GOTTSCHALK Attestng Officer Commissioner of Patents 

